I decided to go ahead and setup a forum for one of the projects I am working on. I already had a zone setup that was hosting a "coming soon" page.
Looking around, I spent quite awhile trying to decide which forum software I was going to use. As a Java developer, I decided to go with a Java-based one so that it is easier for me to maintain. I ended up choosing JForum.
Installation was actually pretty easy. Getting the forums configured not so much (by default new forums were not visible until I went and reconfigured every user group -- each time I added a forum -- very annoying).
I had zlogin'd to the domain and:
# pkg install SUNWj6dvx
# svcadm enable tomcat6
Checking port 8080 on the domain I saw that tomcat was indeed running.
I downloaded jforum-2.1.8.war and placed it as: /var/tomcat6/webapps/jforum.war
Going to http://THEMACHINE:8080/jforum/install.jsp I specified to use HSQLDB, UTF-8, my URLs and a password.
Still a few things I'd like to fix, but as of now the forums are working.